U.S. patent application number 09/754661 was filed with the patent office on 2002-08-29 for combined shaped balloon and stent protector.
Invention is credited to Chen, John Jianhua, Wang, Lixiao.
Application Number | 20020120320 09/754661 |
Document ID | / |
Family ID | 25035772 |
Filed Date | 2002-08-29 |
United States Patent
Application |
20020120320 |
Kind Code |
A1 |
Wang, Lixiao ; et
al. |
August 29, 2002 |
Combined shaped balloon and stent protector
Abstract
A stent delivery catheter comprising a catheter shaft and
balloon engaged thereto. The balloon being inflatable from a first
inflation state to a first expanded state as well as to a second
expanded state. The balloon having a stent mounting region for
retaining and delivery of a stent therefrom, and at least one
adjacent region. The stent mounting region having a first diameter
and the at least one adjacent region having a second diameter. In
the first inflation state the first diameter being less than the
second diameter. In the first expanded state the first diameter
being no greater than the second diameter. In the second expanded
state the first diameter being greater than the second diameter.
The stent being retained on the stent mounting region by engagement
of the at least one adjacent portion and at least one retractable
stent retaining sleeve.
Inventors: |
Wang, Lixiao; (Maple Grove,
MN) ; Chen, John Jianhua; (Plymouth, MN) |
Correspondence
Address: |
VIDAS, ARRETT & STEINKRAUS, P.A.
6109 BLUE CIRCLE DRIVE
SUITE 2000
MINNETONKA
MN
55343-9185
US
|
Family ID: |
25035772 |
Appl. No.: |
09/754661 |
Filed: |
January 4, 2001 |
Current U.S.
Class: |
623/1.11 |
Current CPC
Class: |
A61M 2025/1059 20130101;
A61F 2/958 20130101; A61M 25/1002 20130101; A61F 2002/9583
20130101 |
Class at
Publication: |
623/1.11 |
International
Class: |
A61M 029/00 |
Claims
1. A stent delivery catheter, the catheter comprising: a catheter
shaft, and a balloon, the balloon being mounted to the catheter
shaft, the balloon being inflatable to a first inflation state, to
a second inflation state, the balloon having a stent mounting
region, and an adjacent region, the stent mounting region having a
stent mounting region diameter and the adjacent region having an
adjacent region diameter; the balloon further having an inflation
curve wherein when the balloon is in the first inflation state the
stent mounting region diameter is less than the adjacent region
diameter, in the second inflation state the stent mounting region
diameter is substantially the same as the adjacent region
diameter.
2. The stent delivery catheter of claim 1 further comprising a
stent, the stent being disposed about at least a portion of the
stent mounting region, the stent being expandable from an
unexpanded state to a first stent expanded state, the stent further
comprising a stent center, a first stent end and a second stent
end.
3. The stent delivery catheter of claim 2 further comprising a
stent retaining sleeve, the stent retaining sleeve having a stent
retaining portion removingly disposed about at least one end of the
stent and a catheter engagement portion engaged to a portion of the
catheter shaft adjacent to the balloon.
4. The stent delivery catheter of claim 2 further comprising a
first stent retaining sleeve and a second stent retaining sleeve,
the first stent retaining sleeve having a stent retaining portion
removingly disposed about the first stent end and a catheter
engagement portion engaged to a first portion of the catheter
shaft, the second stent retaining sleeve having a stent retaining
portion removingly disposed about the second stent end and a
catheter engagement portion engaged to a second portion of the
catheter shaft.
5. The stent delivery catheter of claim 4 wherein when the balloon
is expanded from the first inflation state to the second inflation
state the stent is expanded from the unexpanded state to the first
stent expanded state.
6. The stent delivery catheter of claim 5 wherein the stent
mounting region is characterized as having a stepped compliance
curve and the adjacent region is characterized as having a
substantially linear compliance curve, the stepped compliance curve
being characterized by a low pressure segment defined by a low
inflation pressure range, said low pressure segment being generally
collinear with a corresponding segment of the generally linear
compliance curve of the at least one adjacent region which is
defined by said low inflation pressure range, a transition segment
during which the balloon expands rapidly relative to the at least
one adjacent region and a high pressure segment during which the
compliance curve of the stent mounting region expands slowly
relative to the transition segment.
7. The stent delivery catheter of claim 6 wherein when the balloon
is inflated to the second inflation state the stent mounting region
is expanded according to the transition segment of the stepped
compliance curve.
8. The stent delivery catheter of claim 5 wherein when the balloon
is inflated to the second inflation state the stent mounting region
is expanded according to the low pressure segment of the stepped
compliance curve.
9. The stent delivery catheter of claim 4 wherein when the stent is
expanded from the unexpanded state to the first stent expanded
state the first stent retaining sleeve is configured to retract off
of the first stent end, the second stent retaining sleeve is
configured to retract off of the second stent end thereby releasing
the stent from the first and second stent retaining sleeves.
10. The stent delivery catheter of claim 1 wherein the balloon
further comprises a third inflation state, in the third inflation
state the stent mounting region diameter being greater than the
adjacent region diameter.
11. The stent delivery catheter of claim 10 wherein the stent
further comprises a second stent expanded state, such that when the
balloon is expanded to the third inflation state the stent is
expanded to the second stent expanded state.
12. The stent delivery catheter of claim 5 wherein the balloon
further comprises a third inflation state, in the third inflation
state the stent mounting region diameter being greater than the
adjacent region diameter.
13. The stent delivery catheter of claim 12 wherein when the
balloon is inflated to the third inflation state the stent mounting
region is expanded according to the transition segment of the
stepped compliance curve.
14. The stent delivery catheter of claim 12 wherein when the
balloon is inflated to the third inflation state the stent mounting
region is expanded according to the high pressure segment of the
stepped compliance curve.
15. The stent delivery catheter of claim 1 wherein when the balloon
is in the first inflation state the stent mounting region diameter
is about 1.5 mm to about 2.5 mm.
16. The stent delivery catheter of claim 1 wherein when the balloon
is in the first inflation state the adjacent region diameter is
about 1.65 mm to about 2.65 mm.
17. The stent delivery catheter of claim 1 wherein when the balloon
is in the second inflation state the adjacent region diameter has a
range of about 2.0 mm to about 3.75 mm.
18. The stent delivery catheter of claim 10 wherein when the
balloon is in the third inflation state the stent mounting region
diameter has a range of about 2.75 mm to about 4.25 mm and the
adjacent region diameter has a range of about 2.0 mm to 3.75
mm.
19. The stent delivery catheter of claim 1 wherein the balloon is
constructed from at least one member of the group consisting of:
thermoplastic polyurethane, polyethylene, polyesters, poly(butylene
terephthalate)-block-poly(tetramethylene oxide) polymers,
polyetherether ketone, block copolymers of polyether polymers and
polyamides, block copolymers of polyether and polyester polymers,
polyamides, block polyimides, polytetrafluoroethylene, polyolefins,
silicone elastomers, and any combinations thereof.
20. The stent delivery catheter of claim 19 wherein the balloon is
at least partially constructed from PEBAX.
21. The stent delivery catheter of claim 10 wherein when the
balloon is inflated to a first pressure of 1 atm to about 3 atm the
balloon is in the first inflation state, when the balloon is
inflated to a second pressure of more than about 3 atm to about 6
atm the balloon is in the first inflation state, when the balloon
is inflated to a third pressure of about 12 atm to about 16 atm the
balloon is in the third inflation state.
22. The stent delivery catheter of claim 12 wherein when the
balloon is inflated to a first pressure of greater than about 3 atm
to about 6 atm the stent mounting region is in the low pressure
segment of the stepped compliance curve and when the balloon is
inflated to a third pressure of about 12 atm to about 16 atm the
stent mounting region is in the high pressure segment of the
stepped compliance curve.
23. The stent delivery catheter of claim 1 wherein the adjacent
region further comprises a proximal adjacent region and a distal
adjacent region.
24. A stent delivery catheter comprising: a catheter shaft; a
balloon, the balloon being mounted to a distal portion of the
catheter shaft, the balloon being inflatable to a first inflation
state to a second inflation state, the balloon having a stent
mounting region, and a pair of balloon regions adjacent to the
stent mounting region, the pair of balloon regions comprising: a
proximal adjacent region and a distal adjacent region, the stent
mounting region having a stent mounting region diameter and each of
the adjacent regions having an adjacent region diameter, in the
first inflation state the stent mounting region diameter being less
than the adjacent region diameter, in the second inflation state
the stent mounting region diameter being no greater than the
adjacent region diameter; a stent, the stent being disposed about
at least a portion of the stent mounting region, the stent being
expandable from an unexpanded state to a first stent expanded
state, the stent further comprising a stent center, a first stent
end and a second stent end; and a proximal stent retaining sleeve
and a distal stent retaining sleeve, each of the stent retaining
sleeves having a stent retaining portion and a catheter engagement
portion, the stent retaining portion of the distal stent retaining
sleeve being removingly disposed about the first stent end, the
stent retaining portion of the proximal stent retaining sleeve
being removably disposed about the second stent end, the catheter
engagement portion of the distal stent retaining sleeve being
engaged to a portion of the catheter shaft proximate to the distal
adjacent region of the balloon, the catheter engagement portion of
the proximal stent retaining sleeve being engaged to a portion of
the catheter shaft proximate to the proximal adjacent region of the
balloon, whereby when the balloon is inflated from the first
inflation state to the second inflation state the at least one
stent retaining sleeve is retracted off of the at least one end of
the stent.
25. The stent delivery catheter of claim 24 wherein the stent
mounting region of the balloon is characterized as having a stepped
compliance curve.
26. The stent delivery catheter of claim 25 wherein each of the
adjacent regions of the balloon are characterized as having a
substantially linear compliance curve.
27. The stent delivery catheter of claim 24 wherein when the
balloon is in the second inflation state the stent mounting region
diameter is about 0.05 mm to about 0.25 mm less than the adjacent
region diameter.
28. The stent delivery catheter of claim 24 wherein the balloon is
further characterized as having a third inflation state, when the
balloon is inflated to the third inflation state the stent mounting
region diameter is greater than the adjacent region diameter.
29. The stent delivery catheter of claim 24 wherein when the
balloon is in the third inflation state the stent mounting region
diameter is about 0.05 mm to about 0.25 mm greater than the
adjacent region diameter.
30. A stent delivery catheter comprising: a catheter shaft; a
balloon, the balloon being mounted to a distal portion of the
catheter shaft, the balloon being inflatable to a first inflation
state, to a second inflation state, and to a third inflation state,
the balloon having a stent mounting region and a pair of adjacent
end regions, the stent mounting region having a stent mounting
region diameter and the pair of end regions each having an end
region diameter, in the first inflation state the stent mounting
region diameter being less than the end region diameter, in the
second inflation state the stent mounting region diameter being no
greater than the end region diameter, in the third inflation state
the stent mounting region diameter being greater than the end
region diameter; and a stent, the stent being disposed about at
least a portion of the stent mounting region, the stent being
expandable from an unexpanded state to an expanded state, the stent
further comprising a stent center, a first stent end and a second
stent end.
31. The stent delivery catheter of claim 30 further comprising a
pair of stent retaining sleeves, each of the stent retaining
sleeves having: a stent retaining portion removingly disposed about
one of the ends of the stent, an end region overlaying portion and
a catheter engagement portion engaged to a portion of the catheter
shaft adjacent to the balloon, whereby when the balloon is inflated
from the first inflation state to the second inflation state the
stent retaining sleeves are retracted off of the ends of the stent
and the end regions of the balloon.
32. The stent delivery catheter of claim 31 wherein when the
balloon is in the first inflation state and the second inflation
state the pair of end regions are engaged to the first stent end
and the second stent end respectively, thereby preventing
longitudinal movement of the stent relative to the balloon.
33. A method of delivering a stent using the stent delivery
catheter of claim 30 comprising the following steps: inserting the
distal portion of the catheter shaft into a body lumen; advancing
the distal portion of the catheter to a legion sight; inflating the
balloon to the first inflation state; inflating the balloon to the
second inflation state by supplying the balloon with an inflation
pressure of between about 3 to about 7 atmospheres; retracting the
stent retaining sleeves from the ends of the stent and from the
adjacent end regions of the balloon; inflating the balloon from the
second inflation state to the third inflation state by supplying
the balloon with an inflation pressure of between about 12 to about
16 atmospheres, thereby expanding the stent to the stent expanded
state; collapsing the balloon; and withdrawing the distal portion
of the catheter from the body lumen.
34. A medical balloon comprising: a stent mounting region and a
pair of adjacent end regions, the balloon being inflatable from a
first inflation state to a second inflation state, in the first
inflation state the stent mounting region having a diameter less
than that of the adjacent end regions, the stent mounting region
having a first rate of expansion and the at adjacent region having
a second rate of expansion, the first rate of expansion being
greater than the second rate of expansion, whereby when the balloon
is inflated from the first inflation state to the second inflation
state by a predetermined inflation pressure the diameter of the
stent mounting region is at least as large as the diameter of the
adjacent and regions.
35. The medical balloon of claim 34 wherein when the balloon is
expanded from the first inflation state to the second inflation
state the balloon is pressurized to a pressure sufficient to expand
a stent mounted over the stent mounting region to a first stent
expanded state.
36. The medical balloon of claim 34 wherein the stent mounting
region has a stepped compliance curve and each of the end regions
have a substantially linear compliance curve, the stepped
compliance curve being characterized by a low pressure segment
defined by a low inflation pressure range, said low pressure
segment being generally collinear with a corresponding segment of
the generally linear compliance curve of the end regions which is
defined by said low inflation pressure range, a transition segment
during which the balloon expands rapidly relative to the end
regions and a high pressure segment during which the compliance
curve of the stent mounting region expands slowly relative to the
transition segment.
37. The medical balloon of claim 36 wherein when the balloon is
inflated to the second inflation state the stent mounting region is
expanded according to the transition segment of the stepped
compliance curve.
38. The medical balloon of claim 36 wherein when the balloon is
inflated to the second inflation state the stent mounting region is
expanded according to the low pressure segment of the stepped
compliance curve.
39. The medical balloon of claim 34 wherein the balloon further
comprises a third inflation state, in the third inflation state the
diameter of the stent mounting region is greater than the diameter
of the at least one adjacent region.
40. The medical balloon of claim 39 wherein when the balloon is
inflated to the third inflation state the stent mounting region is
expanded according to a transition segment of the stepped
compliance curve.
41. The medical balloon of claim 39 wherein when the balloon is
inflated to the third inflation state the stent mounting region is
expanded according to the high pressure segment of the stepped
compliance curve.
42. The medical balloon of claim 34 wherein when the balloon is in
the first inflation state the diameter of the stent mounting region
is about 1.5 mm to about 2.5 mm.
43. The medical balloon of claim 34 wherein when the balloon is in
the first inflation state the end regions have a diameter of about
1.65 mm to about 2.65 mm.
44. The medical balloon of claim 34 wherein when the balloon is in
the second inflation state the end regions have a diameter of about
2.0 mm to about 3.75 mm.
45. The medical balloon of claim 34 wherein when the balloon is in
the third inflation state the diameter of the stent mounting region
is about 2.75 mm to about 4.25 mm and the end regions have a
diameter of about 2.0 mm to 3.75 mm.
46. The medical balloon of claim 34 wherein the stent mounting
region has a hardness value greater than that of the adjacent end
regions.
47. The medical balloon of claim 34 further comprising a coating,
the coating being positioned on at least a portion of the adjacent
end regions of the balloon and not on the stent mounting region,
the coating effective to restrict expansion of the end regions at
the predetermined inflation pressure..
48. The medical balloon of claim 52 wherein the coating is selected
from at least one member of the group consisting of:, poly(ethylene
terephthalate) (commonly referred to as PET), polyimide,
thermoplastic polyimide, polyamides, polyesters, polycarbonates,
polyphenylene sulfides, polypropylene and rigid polyurethanes.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] Not Applicable
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH
[0002] Not Applicable
BACKGROUND OF THE INVENTION
[0003] 1. Field of the Invention
[0004] The present invention relates generally to a method of
installing a stent utilizing a balloon catheter to perform an
initial angioplasty and to seat the stent after it has been located
in the vessel. The invention also relates to novel balloon
structures which have particular use in the method of the
invention. More specifically, this invention relates to a stent
delivery system wherein at least a portion of the balloon is step
compliant which provides the balloon with the ability to expand
specific portions of the balloon at different times according to a
variety of inflation pressures. In addition the unique shape of the
balloon may be configured to engage the stent throughout the
insertion as well as the delivery procedures which in turn reduces
longitudinal movement of an associated medical device such as a
stent, stent-graft, graft or vena cava filter mounted on the
balloon both prior to and during balloon expansion.
[0005] 2. Description of the Related Art
[0006] Expandable, implantable medical devices such as stents are
utilized in a number of medical procedures and situations as are
stent delivery assemblies. As such, their structure and function
are well known. A stent is a generally cylindrical prosthesis
introduced via a catheter into a lumen of a body vessel in a
configuration having a generally reduced diameter and then expanded
to the diameter of the vessel. The stent may be self-expanding,
such as a NITINOL shape memory stent, or it may be expandable by
means of an inflatable portion of the catheter, such as a balloon.
In its expanded configuration, the stent supports and reinforces
the vessel walls while maintaining the vessel in an open,
unobstructed condition.
[0007] Self-expanding, inflation assisted expandable and inflation
expandable stents are well known and widely available in a variety
of designs and configurations. Inflation expandable and inflation
assisted expandable stents are expanded via outward radial pressure
such as that provided by a balloon disposed underneath the stent
during inflation of the balloon.
[0008] Medical device delivery balloons may have a variety of
shapes, sizes, inflation characteristics and a variety of other
performance attributes. Some examples of balloons which may be used
for the expansion and delivery of a medical device are described in
U.S. Pat. No. 5,556,383; U.S. Pat. No. 5,738,901; U.S. Pat. No.
6,024,752; and U.S. Pat. No. 6,048,350.
[0009] In advancing an inflation expandable stent through a body
vessel to the deployment site, there are a number of important
considerations. The stent must be able to securely maintain its
axial position on the delivery catheter, without translocating
proximally or distally, and especially without becoming separated
from the catheter. Furthermore, it may be desirable to protect the
distal and proximal ends of the stent to prevent distortion of the
stent and to prevent abrasion and/or to reduce potential trauma to
the vessel walls.
[0010] To address the concerns stated above, one approach has been
identified which utilizes a retractable sheath or sheaths which are
disposed about the distal end of the catheter and cover the stent
and balloon. In such devices the sheath is retracted prior to the
inflation of the balloon and subsequent delivery of the stent.
Another solution involves the utilization of one or more stent
retaining means such as elastomeric sleeves or socks. The socks are
disposed about the ends of the stent and the respective adjacent
portions of the catheter shaft. Socks may be constructed such that
during balloon inflation the socks release the stent as a result of
the forces and change in geometry resulting from the expanding
balloon. It is also known that socks may be constructed to retract
or be pulled off of the stent as a result of their construction and
the expansion of the balloon.
[0011] Inflation expandable stent delivery and deployment
assemblies are known which utilize restraining means that overlie
the stent during delivery. U.S. Pat. No. 4,950,227 to Savin et al.,
relates to an inflation expandable stent delivery system in which a
sleeve overlaps the distal or proximal margin (or both) of the
stent during delivery. During inflation of the stent at the
deployment site, the stent margins are freed of the protective
sleeve(s). U.S. Pat. No. 5,403,341 to Solar, relates to a stent
delivery and deployment assembly which uses retaining sheaths
positioned about opposite ends of the compressed stent. The
retaining sheaths of Solar are adapted to tear under pressure as
the stent is radially expanded, thus releasing the stent from
engagement with the sheaths. U.S. Pat. No. 5,108,416 to Ryan et
al., describes a stent introducer system which uses one or two
flexible end caps and an annular socket surrounding the balloon to
position the stent during introduction to the deployment site. The
content of all references, including patents and patent
applications are respectively incorporated it their entirety herein
by reference.
[0012] Providing a means for containing and securing the stent or
other medical device on the balloon catheter prior to inflation is
but one problem facing stent delivery systems. An additional
concern is the shifting or sliding of the stent relative to the
balloon during balloon expansion. Numerous attempts have been made
to reduce or prevent translocation of the stent on the balloon
during balloon expansion. For example: copending U.S. patent
application Ser. No. 09/667,916, filed Sep. 22, 2000 and entitled
Coated Stents with Better Gripping Ability, describes a stent
coating which provides the stent with improved ability to adhere to
the balloon during the expansion process. Another example is U.S.
Pat. No. 5,836,965 which describes a process wherein a balloon is
expanded and heat set then allowed to cool in order to adhere the
balloon to the stent. Yet another example is co-pending U.S. patent
application Ser. No. 08/740,727, filed Nov. 1, 1996 and entitled
Selective Coating Of A Balloon Catheter With Lubricous Material For
Stent Deployment, which describes a balloon having a tacky coating
for securing a stent to a balloon prior to delivery.
[0013] Angioplasty, an accepted and well known medical practice
involves inserting a balloon catheter into the blood vessel of a
patient, maneuvering and steering the catheter through the
patient's vessels to the site of the lesion with the balloon in an
uninflated form. The uninflated balloon portion of the catheter is
located within the blood vessel such that it crosses the lesion or
reduced area. Pressurized inflation fluid is metered to the
inflatable balloon through a lumen formed in the catheter to thus
dilate the restricted area. The inflation fluid is generally a
liquid and is applied at relatively high pressures, usually in the
area of six to twenty atmospheres. As the balloon is inflated it
expands and forces open the previously closed area of the blood
vessel. Balloons used in angioplasty procedures such as this are
generally fabricated by molding and have predetermined design
dimensions such as length, wall thickness and nominal diameter.
Balloon catheters are also used in other systems of the body for
example the prostate and the urethra. Balloon catheters come in a
large range of sizes and must be suitably dimensioned for their
intended use.
[0014] Recently the use of a catheter delivered stent to prevent an
opened lesion from reclosing or to reinforce a weakened vessel
segment, such as an aneurism, has become a common procedure. A
typical procedure for stent installation involves performing an
initial angioplasty to open the vessel to a predetermined diameter
sufficient to permit passage of a stent delivery catheter across
the lesion, removal of the angioplasty balloon catheter, insertion
of a delivery catheter carrying the stent and a stent deploying
mechanism, deploying the stent across the opened lesion so as to
separate the stent from the catheter and bring it into contact with
the vessel wall, usually with dilation to a lager diameter using a
balloon larger than the balloon of the predilation catheter, and
then removing the delivery catheter (after deflating the balloon if
used). In many cases it has become the practice to then "retouch"
the dilation by deploying a third catheter carrying a balloon
capable of dilating at a substantially higher pressure to drive the
stent into the vessel wall, thereby to assure that there is no risk
of the stent later shifting its position and to reduce occurrence
of restenosis or thrombus formation. This third "retouch" dilation
is often considered necessary when the balloon used to seat the
stent is made of a compliant material because such balloons
generally cannot be safely pressurized above 9-12 atm., and higher
pressures are generally considered necessary to assure full uniform
lesion dilation and seating of the stent.
[0015] A wide variety of stent configurations and deployment
methods are known. For instance, stent configurations include
various forms of bent wire devices, self-expanding stents; stents
which unroll from a wrapped configuration on the catheter; and
stents which are made of a deformable material so that the device
may be deformed on deployment from a small diameter to a larger
diameter configuration. References disclosing stent devices and
deployment catheters include:
1 U.S. Pat. No. 4733665 Palmaz U.S. Pat. No. 4856516 Hillstead U.S.
Pat. No. 4776337 Palmaz U.S. Pat. No. 4922905 Strecker U.S. Pat.
No. 5195984 Schatz U.S. Pat. No. 4886062 Wiktor U.S. Pat. No.
5234457 Andersen U.S. Pat. No. 4907336 Gianturco U.S. Pat. No.
5116360 Pinchuck et al U.S. Pat. No. 4913141 Hillstead U.S. Pat.
No. 5116318 Hillstead U.S. Pat. No. 5092877 Pinchuk U.S. Pat. No.
4649922 Wiktor U.S. Pat. No. 5123917 Lee U.S. Pat. No. 4655771
Wallsten U.S. Pat. No. 5116309 Coll U.S. Pat. No. 5089006 Stiles
U.S. Pat. No. 5122154 Rhodes U.S. Pat. No. 5007926 Derbyshire U.S.
Pat. No. 5133732 Wiktor U.S. Pat. No. 4705517 DiPisa, Jr. U.S. Pat.
No. 5135536 Hillstead U.S. Pat. No. 4740207 Kreamer U.S. Pat. No.
5282824 Gianturco U.S. Pat. No. 4877030 Beck et al U.S. Pat. No.
5292331 Boneau U.S. Pat. No. 5108417 Sawyer U.S. Pat. No. 5035706
Gianturco et al U.S. Pat. No. 4923464 DiPisa, Jr U.S. Pat. No.
5041126 Gianturco U.S. Pat. No. 5078726 Kreamer U.S. Pat. No.
5061275 Wallsten et al U.S. Pat. No. 5171262 MacGregor U.S. Pat.
No. 5064435 Porter U.S. Pat. No. 5059211 Stack et al U.S. Pat. No.
5092841 Spears U.S. Pat. No. 5104399 Lazarus U.S. Pat. No. 5108416
Ryan et al U.S. Pat. No. 5104404 Wolff U.S. Pat. No. 4990151
Wallsten U.S. Pat. No. 5019090 Pinchuk U.S. Pat. No. 4990155
Wilkoff U.S. Pat. No. 4954126 Wallsten U.S. Pat. No. 4969890 Sugita
et al U.S. Pat. No. 4994071 MacGregor U.S. Pat. No. 4795458 Regan
U.S. Pat. No. 4580568 Gianturco U.S. Pat. No. 4760849 Kropf U.S.
Pat. No. 4681110 Wiktor U.S. Pat. No. 5192297 Hull U.S. Pat. No.
4800882 Gianturco U.S. Pat. No. 5147385 Beck et al U.S. Pat. No.
4830003 Wolff et al U.S. Pat. No. 5163952 Froix
[0016] In U.S. Pat. No. 5,348,538, the entire contents of which
being incorporated herein by reference, there is described a single
layer balloon which follows a stepped compliance curve. The stepped
compliance curves of these balloons has a lower pressure segment
following a first generally linear profile, a transition region,
typically in the 8-14 atm range, during which the balloon rapidly
expands yielding in elastically, and a higher pressure region in
which the balloon expands along a generally linear, low compliance
curve. The stepped compliance curve allows a physician to dilate
different sized lesions without using multiple balloon
catheters.
[0017] Stepped compliance curve catheter balloon devices using two
different coextensively mounted balloon portions of different
initial inflated diameter, are also described in U.S. Pat. No.
5,447,497 and in U.S. Pat. No. 5,358,487 to Miller. These dual
layer balloons are designed with the outer balloon portion larger
than the inner portion so that the compliance curve follows the
inner balloon portion until it reaches burst diameter and then,
after the inner balloon bursts, the outer balloon becomes inflated
and can be expanded to a larger diameter than the burst diameter of
the inner balloon.
[0018] A polyethylene ionomer balloon with a stepped compliance
curve is disclosed in EP 540 858. The reference suggests that the
balloon can be used on stent delivery catheters. The disclosed
balloon material of this reference, however, yields a compliant
balloon and therefore a stent delivered with such a balloon would
typically require "retouch."
[0019] Balloons having a stepped compliance curve have also been
described for use in stent delivery. Two examples of such stent
delivery balloons and methods of their use are described in U.S.
Pat. No. 5,749,851 and U.S. Pat. No. 5,980,532, respectively
incorporated in their entirety herein by reference.
[0020] The entire content of all of the patents and patent
applications listed within the present patent application are
respectively incorporated in their entirety herein by
reference.
BRIEF SUMMARY OF THE INVENTION
[0021] The invention in one aspect is directed to a medical
balloon. More specifically, the present invention is directed to a
stent delivery system employing a unique stepped compliant balloon
which is shaped to retain a stent about a stent mounting region of
the balloon prior to and during stent delivery. The balloon is
capable of providing low pressure predilation at a relatively small
diameter to open the lesion sufficiently to allow insertion and
deployment of the stent across the lesion and for subsequent high
pressure embedding of the stent in the vessel wall. The same
balloon catheter may also be employed to insert and deploy the
stent. Thus at least one catheter may be eliminated from what may
otherwise be a two or three catheter installation process.
[0022] In at least one embodiment of the invention, the balloon of
the invention may be made by molding a balloon into a configuration
in which the second portion has a larger diameter than the first
portion and then shrinking the second portion to the diameter of
the first portion or less than the diameter of the first portion.
The method of making such balloons comprises yet another aspect of
the invention.
[0023] In at least one embodiment of the invention the, the balloon
may be incorporated into a stent delivery catheter, wherein a stent
mounting region of the balloon has a diameter less than the
diameter of the balloon ends, whereby the stent is prevented from
longitudinal migration relative to the catheter as a result of
interference provided by the balloon ends. The balloon may be
configured to expand so that the stent remains held in place during
balloon expansion.
[0024] In at least one embodiment of the invention the balloon is
configured to have a first inflation state, a second inflation
state, and a third or fully inflated state.
[0025] In yet another embodiment of the invention the balloon may
be configured to expand such that the balloon ends maintain a
larger diameter than the stent mounting region until a
predetermined inflation pressure is achieved, whereupon the stent
mounting region may expand to a diameter greater than the diameter
of the balloon ends.
[0026] In yet another aspect of the invention a stent delivery
catheter may employ a stepped compliant balloon and one or more
stent retaining sleeves. The balloon may be configured such that
the balloon ends inflate sufficiently to cause the sleeves to
retract, whereupon the stent mounting region expands to release the
stent.
[0027] These and other more detailed and specific objectives and an
understanding of the invention will become apparent from a
consideration of the following Detailed Description of the
Invention in view of the Drawings. Other embodiments may also be
apparent, but which are not described in detail, from the following
description.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0028] A detailed description of the invention is hereafter
described with specific reference being made to the drawings in
which:
[0029] FIG. 1 is a side view of an embodiment of the invention as
depicted within a body vessel;
[0030] FIG. 2 is a side view of an embodiment of the invention
wherein the balloon is depicted in a first inflation state;
[0031] FIG. 3 is a side view of the embodiment of the invention
shown in FIG. 2, wherein the balloon is depicted in the second
inflation state;
[0032] FIG. 4 is a side view of an alternative embodiment of the
invention, wherein the balloon is depicted in the second inflation
state;
[0033] FIG. 5 is a side view of an embodiment of the invention
wherein the balloon is shown in the third inflation state;
[0034] FIG. 6 is a side view of an embodiment of the invention
which includes a pair of retractable stent retaining sleeves;
[0035] FIG. 7 is a side view of the embodiment of the invention
shown in FIG. 6 wherein the balloon is in the second inflation
state and the sleeves are retracted;
[0036] FIG. 8 is a side view of an embodiment of the invention
which includes a single retractable stent retaining sleeve;
[0037] FIG. 9 is a side view of the balloon shown in FIG. 8 shown
in the first inflation state;
[0038] FIG. 10 is a side view of the balloon shown in FIG. 9 shown
in the second inflation state;
[0039] FIG. 11 is a side view of the balloon shown in FIG. 10 shown
in the third inflation state;
[0040] FIG. 12 is a side view of an embodiment of the balloon shown
in the first inflation state;
[0041] FIG. 13 is a side view of the balloon shown in FIG. 12 shown
in the second inflation state; and
[0042] FIG. 14 is a side view of the balloon shown in FIG. 13 shown
in the third inflation state.
DETAILED DESCRIPTION OF THE INVENTION
[0043] The catheters employed in the practice of the present
invention are most conveniently constructed as over-the-wire
balloon catheters of conventional form for use in angioplasty,
except that the balloon has a stepped compliance curve. However it
should be understood that the present invention can be applied, in
addition to over-the-wire catheters, to fixed-wire catheters, to
shortened guide wire lumens or single operator exchange catheters,
and to non over-the-wire balloon catheters. Furthermore this
invention can be used with balloon catheters intended for use in
any and all vascular systems of cavities of the body.
[0044] As may be seen in FIG. 1, the present invention is directed
to a stent delivery catheter, indicated generally at 10, which
employs a balloon 12 which is mounted to a distal portion 20 of the
catheter shaft 28. In the present invention, the balloon 12
includes a stent mounting region 14 and a pair of adjacent end
portions 16.
[0045] A stent 18 is disposed about the stent mounting region 14
prior to stent delivery. The stent 18 is delivered by advancing the
distal portion 20 of the catheter 10 through a body lumen or vessel
22 to a legion site 24. The balloon 12 is then inflated to
predetermined pressure to expand the stent to a fully expanded
state
[0046] As is know to those of skill in the art, when a medical
balloon of catheter is in the non-inflated state, the balloon will
typically include one or more folds. The folded configuration of
the balloon provides numerous benefits to the catheter device. An
example of a folded balloon is described in U.S. patent application
Ser. No. 09/335,361, filed Jun. 17, 1999 and entitled Stent
Securement By Balloon Modification, the entire contents of which
being incorporated herein by reference. The balloon 12 depicted in
FIG. 1 is shown in what is referred to herein as the first
inflation state. However, the first inflation state is considered
for purposes of this application to be an inflation state wherein
the balloon 12 has been unfolded by an internal inflation pressure
of about 1 to about 3 atmospheres. Despite, being "unfolded" by
such pressure, the balloon 12 as shown in FIG. 1 is not yet
expanded and is thus may be characterized as being unexpanded or
nominally inflated.
[0047] As may be seen in FIGS. 2-5 the balloon 12 may be
characterized as having at least two inflation states in addition
to the first inflation state shown in FIG. 1. In FIG. 2, the
balloon 12 is shown in the first inflation state; in FIG. 3 and 6,
the balloon 12 is respectively shown in alternative second
inflation states, and in FIG. 5, the balloon 12 is shown in a third
inflation state.
[0048] As may be seen in FIG. 2, when the balloon 12 is in the
first inflation state, the catheter as a whole has a low profile
sufficient for allowing the distal portion 20 of the catheter 10 to
advance through a body lumen. In the first inflation state the
stent mounting region 14 of the balloon 12 will typically have a
diameter less than about 2.5 mm. The diameter of the stent mounting
region may also range from about 1.5 mm to about 2.5 mm. In the
first inflation state, the diameter of the end region(s) 16 will be
greater than the diameter of the stent mounting region 14. The end
region(s) 16 will typically be between about 1.65 mm to about 2.65
mm in diameter depending on the diameter of the stent mounting
region 14.
[0049] The balloon 12 is inflated by injecting a fluid or other
inflation means into the balloon 12. Typically the catheter 10 will
be equipped with one or more inflation lumens (not shown) which are
in fluid communication with the balloon and the proximal end of the
catheter (not shown). Lumens as well as inflation means for
balloons, including the present catheter balloon are well known in
the art.
[0050] It may also be seen that in the embodiment shown in FIG. 2,
the catheter 10 is equipped with marker bands 40. Marker bands may
be used to denote the location of the stent on the catheter as well
as to serve as a means of determining the location of the distal
end of the catheter as it advances through the body. The marker
bands are typically constructed of radiopaque materials. Examples
of suitable marker bands are described in U.S. application Ser. No.
09/327,234 entitled Radiopaque Bands and filed Jun. 7, 1999, the
entire contents of which being incorporated herein by
reference.
[0051] As the balloon 12 is inflated, the balloon 12 will expand
the stent 18. As may be seen in FIG. 3, the balloon 12 has been
inflated to a second inflation or inflated state. In the second
inflation state the balloon 12 may be configured to provide the
stent mounting region 14 and the end regions 16 with substantially
the same diameter such as is shown. However, in the embodiment
illustrated in FIG. 4, when the balloon 12 is in the second
inflation state, the diameter of the stent mounting region 14
remains less than the diameter of the end regions 16. In the second
inflation state the diameter of the stent mounting region may range
from about 3.0 to about 3.6 mm, in alternative embodiments however,
the diameter may be less. Where the balloon is configured to have
end regions 16 which have diameters greater than the diameter of
the stent mounting region 14 the diameter of the end portions will
typically be about 0.1 mm to about 1 mm greater than the diameter
of the stent mounting region 14.
[0052] By providing the balloon 12 with end regions 16 that have a
greater diameter than that of the stent mounting region 14, the end
portions may be utilized to engage the ends 25 and 26 of the stent
18 thereby ensuring that the stent 18 does not migrate
longitudinally relative to the balloon 12. By providing such
enlarged end regions in both the first inflation state, such as is
shown in FIG. 2 as well as in the second inflation state, such as
is shown in FIG. 4, the position of the stent 18 remains constant
on the balloon 12 during insertion and advancement of the catheter
10 as well as during balloon inflation.
[0053] Subsequent to inflating the balloon 12 to a second inflation
state, such as is shown in FIGS. 3 and 4, the balloon 12 may be
further inflated to a third inflation state, such as is shown in
FIG. 5.
[0054] As previously described the balloon 12 may be at least
partially stepped compliant. In the embodiments discussed thus far
the stent mounting region 14 is characterized as having a stepped
compliance curve where as the adjacent end region(s) may be
characterized as having a substantially linear compliance curve.
Examples and description of a stepped compliant curves as well as a
substantially linear compliance curve are described in U.S. Pat.
No. 5,632,760 and U.S. Pat. No. 5,980,532, both of which are
incorporated in their respective entireties herein by reference.
Typically, a stepped compliance curve may be characterized by a
first or low pressure segment defined by a low inflation pressure
range. In the present invention, the low pressure segment of the
stepped compliance curve of the stent mounting region 14 is
generally collinear with a corresponding segment of the generally
linear compliance curve of the end portions 16 which is defined by
said low inflation pressure range. The stepped compliance curve of
the stent mounting regions 16 may also include a transition segment
during which the balloon expands rapidly relative to the at least
one adjacent region and a high pressure segment during which the
compliance curve of the stent mounting region expands slowly
relative to the transition segment.
[0055] In the third inflation state the balloon 12 is inflated with
pressure from about 12 to about 16 atmospheres. The greater
pressure of the third inflation state corresponds to the high
pressure segment of the compliance cure. The balloon 12 is
constructed such that when the balloon 12 is inflated to the third
inflation state, only the diameter of the stent mounting region 14
will continue to expand according to the high pressure segment of
the stepped compliance curve. The diameter of the end regions 16
will exhibit only nominal expansion if at all when the balloon 12
is inflated to the third inflation state.
[0056] Alternatively, the balloon 12 may be characterized as having
a stent mounting region 14 which has a higher rate of expansion
than the rate of expansion of the end regions 16. Such that when
the balloon 12 is inflated with a predetermined inflation pressure,
the stent mounting region 14 will inflate to a greater degree than
the end portions 16. Numerous methods could be applied to the
balloon of the present invention to achieve different inflation
rates. For example the end regions 16 could incorporate a
relatively hard coating and/or additional materials such as the
relatively stiff high pressure polymeric materials, such as
thermoplastic polymers and thermoset polymeric materials,
poly(ethylene terephthalate) (commonly referred to as PET),
polyimide, thermoplastic polyimide, polyamides, polyesters,
polycarbonates, polyphenylene sulfides, polypropylene and rigid
polyurethanes. Such materials or coatings could be applied to a
portion of the end region 16 to provide the region(s) 16 with a
reduced rate of inflation relative to the stent mounting region 14.
In addition, one or both expansion rates may also be characterized
as being stepped compliant as described above.
[0057] In an alternative embodiment shown in FIG. 6, the catheter
10 may be equipped with retractable stent retaining sleeves 30 and
32. Each of the sleeves 30 and 32 have three portions: a catheter
engagement portion 34, an balloon end region overlaying portion 36,
and a stent end overlaying portion 38. The catheter engagement
portion 34 is engaged to a portion of the catheter shaft 28
adjacent to the balloon 12. The sleeves 30 and 32 may be engaged to
the catheter in any manner known. For example the sleeves may be
frictionally engaged, adhesively bonded, chemically or heat welded
or other wise attached to the catheter shaft 28. The end overlaying
portion 36 of each sleeve is slidingly disposed about the end
region 16 of the balloon 12. The stent end overlaying region 38 of
each sleeve 30 and 32, extends on to the stent mounting region 14
of the balloon 12 and respectively overlays stent ends 25 and 26.
The stent end overlaying region 38 of each sleeve 30 and 32 retains
the stent 18 on the stent mounting region 14 of the balloon 12
prior to stent delivery.
[0058] As may be seen in FIG. 7, when the balloon 12 is inflated to
the second inflation state, the sleeves 30 and 32 are retracted off
of the respective stent ends 25 and 26 to release the stent.
[0059] In the embodiments shown in FIGS. 3, 4 and 7, the balloon 12
may be inflated to the third inflation state as is shown in FIG. 5.
In addition the sleeves 30 and 32 may be configured to retract off
of the stent ends 25 and 26 when the balloon 12 is in the third
inflation state rather than the second inflation state.
[0060] Alternatively, the catheter 10 may include a single sleeve
30 such as may be seen in FIG. 8.
[0061] In another alternative embodiment of the invention may be
seen in FIGS. 9-11, the invention may be directed exclusively to
the inventive balloon 12 such as balloon 12 shown in FIG. 1. In the
present embodiment, the balloon 12 is shown with a stent mounting
region 14 distally adjacent to a single end portion 16, such as may
also be seen in FIG. 8. In FIGS. 9-11 the balloon 12 is shown
respectively in the first inflation state, the second inflation
state and the third inflation state. The balloon 12 may be
incorporated into a balloon catheter or a stent delivery catheter
such as those previously shown and described above, or as may be
known in the art.
[0062] Similar to the embodiments shown in FIGS. 9-11, the
alternative embodiments shown in FIGS. 12-14 are directed to the
balloon 12 portion of the catheter such as is shown in FIGS. 2-4
above. In the embodiments shown in FIGS. 12-14, the balloon 12 has
a distal adjacent end 16 and a proximal adjacent end 17 which
surround the stent mounting region 14. As with the previous
embodiments, the embodiments shown in FIGS. 12-14 may be
incorporated into any type of balloon catheter or stent delivery
catheter especially those described herein. The balloon 12 of FIGS.
9-14 may include the same inflation characteristics as the balloons
12 of the various embodiments of the invention previously
described.
[0063] In all of the embodiments described herein, if a stent is
utilized with the balloon 12 the stent may be deployed from the
second inflation state by simply collapsing the balloon subsequent
to achieving the second inflation state, such as is depicted in
FIGS. 3, 4 and 7. However, the stent may be further expanded by
inflating the balloon 12 to the third inflation state. By further
expanding the stent 18 in this manner the balloon 12 may be used to
predilate a vessel by expanding to the second inflation state, and
then seating the stent in place by expanding the balloon 12 to the
third inflation state such as is shown in FIG. 5.
[0064] The balloon 12 of the various embodiments discussed herein
should be made of a thermoplastic polymer material which has a high
strength, and gives a low compliance balloon at pressures above
about 15 atmospheres. For purposes of this application "low
compliance" is considered to correspond to a diameter increase of
no more than 0.1 mm per increased atmosphere of pressure,
preferably less than 0.06 mm/atm. Suitably the balloon polymer is
poly(ethylene terephthalate) (PET) of initial intrinsic viscosity
of at least 0.5, more preferably 0.7-0.9. Other high strength
polyester materials, such as poly(ethylene napthalenedicarboxylate)
(PEN), nylons such as nylon 11 or nylon 12, thermoplastic
polyimides and high strength engineering thermoplastic
polyurethanes such as Isoplast 301 sold by Dow Chemical Co., and
Pebax.TM. (a block copolymer polyamide and polyether) made by Elf
Atochem. are considered suitable alternative materials. Desirably
the balloon is blown in a way which will give a wall strength of at
least 18,000 psi, preferably greater than 20,000 psi. Techniques
for manufacturing balloons with such wall strengths are well
known.
[0065] After being blown, the stent mounting region 14 of the
balloon 12 is provided with a stepped compliance curve by annealing
the balloon for a short time after blowing at a pressure at or only
slightly above ambient and at a temperature which causes the blown
balloon to shrink. The process is described in U.S. Pat. No.
5,348,538, incorporated in its entirety herein by reference.
However, the balloons of the invention are desirably constructed
with a greater difference between the low pressure and high
pressure linear regions of the compliance curve so that the
transition between the two regions results in a step-up of diameter
of the balloon of at least 0.4 mm. This is accomplished by blowing
the balloon to the larger diameter and then shrinking to a greater
extent than was done in the specific illustrative examples of U.S.
Pat. No. 5,348,538. The amount of shrinkage is controlled by the
pressure maintained in the balloon during annealing and the
temperature and time of the annealing. For a balloon made from 0.74
intrinsic viscosity PET, the blowing pressure is suitably in the
range 200-400 psi, and temperature is suitably in the range of
90-100.degree. C., and the annealing pressure is in the range of
0-20, preferably 5-10 psi at 90-100.degree. for 3-10 seconds.
[0066] In a further aspect of the invention, the balloons employed
in the inventive process are configured so that the stent mounting
region 14 of the balloon 12 has a stepped compliance curve and the
remainder of the balloon, specifically the end region(s) 16 have an
unstepped or substantially linear compliance curve, the low
pressure regions of the compliance curves of both the stent
mounting region 14 and the end region(s) 16 being generally
collinear.
[0067] The invention may also be practices by use of dual layer
balloons such as described in co-pending U.S. application Ser. No.
08/243,473, filed May 16, 1994 as a continuation of now abandoned
U.S. application Ser. No. 07/927,062, filed Aug. 8, 1992,
incorporated herein by reference, and in U.S. Pat. No. 5,358,487,
incorporated herein by reference. Suitably both balloons of the
dual layer balloons are low compliance balloons designed with the
outer balloon portion larger by at least 0.25 mm than the inner
portion and the inner balloon designed to burst at a pressure below
about 15 atm so that the compliance curve follows the inner balloon
portion until it reaches burst diameter and then, after the inner
balloon bursts, the outer balloon becomes inflated and can be
expanded to a larger diameter than the burst diameter of the inner
balloon.
[0068] Although the present invention has been described in terms
of specific embodiments, it is anticipated that alterations and
modifications thereof will no doubt be come apparent to those
skilled in the art. It is therefore intended that the following
claims be interpreted as covering all such alterations and
modifications as fall within the true spirit and scope of the
invention.
[0069] In addition to being directed to the embodiments described
above and claimed below, the present invention is further directed
to embodiments having different combinations of the features
described above and claimed below. As such, the invention is also
directed to other embodiments having any other possible combination
of the dependent features claimed below.
[0070] The above examples and disclosure are intended to be
illustrative and not exhaustive. These examples and description
will suggest many variations and alternatives to one of ordinary
skill in this art. All these alternatives and variations are
intended to be included within the scope of the attached claims.
Those familiar with the art may recognize other equivalents to the
specific embodiments described herein which equivalents are also
intended to be encompassed by the claims attached hereto.
* * * * *